Transmit emission control in a wireless transceiver
View Patent ↗Methods and apparatus for control of uplink resource allocation and undesirable transmit emissions from a wireless transceiver in a frequency division duplex (FDD) or hybrid frequency division duplex (H-FDD) wireless system. The bandwidths spanned by the receive band and the transmit band may be symmetric or asymmetric. Additionally, each of the receive band or the transmit band may be contiguous or may be an aggregate of multiple discontinuous frequency bands. The wireless transceiver can control undesirable transmit emissions from occurring in a predetermined frequency band by using an offset LO frequency and restricting transmit signals to frequencies away from the predetermined frequency band. Alternatively, in an asymmetric FDD system where a receive band is larger than a transmit band, the transceiver can limit transmit signal allocation to the transmit band. The transceiver can further limit out of band transmit emissions using an offset LO frequency.
1. A method of transmit emission control in a wireless transceiver, the method comprising:
receiving wireless downlink signals in a downlink frequency band;
determining a virtual uplink resource allocation within a virtual uplink frequency band that is distinct from the downlink frequency band and that has a substantially identical bandwidth as the downlink frequency band;
remapping the virtual uplink resource allocation to an uplink resource allocation in an uplink frequency band that is narrower than the virtual uplink frequency band; and
transmitting an uplink signal on the uplink resource allocation.
2. The method of claim 1 , wherein receiving the wireless downlink signals comprises receiving downlink signals in a first time period exclusive of a second time period for transmitting the uplink signal.
3. The method of claim 1 , wherein receiving the wireless downlink signals comprises receiving an uplink control message having the virtual uplink channel allocation.
4. The method of claim 1 , further comprising filtering the uplink signal based on a bandwidth of the uplink resource allocation.
5. The method of claim 3 , wherein the virtual uplink resource allocation is restricted to a portion of the virtual uplink frequency band corresponding to the uplink frequency band.
6. The method of claim 1 , wherein a number and a spacing of subcarriers in the downlink frequency band coincide with a number and a spacing of subcarriers in the virtual uplink frequency band.
7. The method of claim 1 , wherein remapping the virtual uplink resource allocation comprises:
configuring a Local Oscillator (LO) frequency at a frequency offset from a nominal LO frequency for the virtual uplink band; and
remapping the virtual uplink resource allocation based on the frequency offset.
8. The method of claim 1 , wherein remapping the virtual uplink resource allocation comprises remapping a virtual uplink subcarrier index based in part on a difference between a number of subcarriers in the uplink frequency band and a number of subcarriers in the virtual uplink band.
9. The method of claim 1 , further comprising nulling a predetermined subcarrier.
10. The method of claim 9 , wherein the predetermined subcarrier comprises a DC subcarrier in the uplink frequency band.
11. The method of claim 9 , wherein nulling the predetermined subcarrier comprises omitting symbols that map to a DC subcarrier in the uplink frequency band.
12. A method of transmit emission control in a wireless transceiver, the method comprising:
receiving wireless downlink signals in a downlink frequency band, wherein the downlink frequency band is distinct from an uplink frequency band;
determining an virtual uplink resource allocation based on a control message received in the downlink frequency band, the virtual uplink resource allocation restricted to a portion of the uplink frequency band;
remapping the virtual uplink resource allocation to an uplink resource allocation based on a frequency offset that is based in part on a difference between the uplink frequency band and the portion of the uplink frequency band to which the uplink resource allocation is restricted; and
transmitting an uplink signal over the uplink resource allocation.
13. The method of claim 12 , wherein receiving wireless downlink signals comprises receiving the downlink signals in a receive time period that is distinct from a transmit time period.
14. The method of claim 12 , further comprising filtering the uplink signal based in part on a bandwidth of the portion of the uplink frequency band to which the uplink resource allocation is restricted.
15. The method of claim 12 , wherein remapping the virtual uplink resource allocation based on the frequency offset comprises remapping the uplink bandwidth allocation based on a frequency offset that positions a center frequency of the uplink frequency band away from a constrained emissions band.
16. A method of transmit emission control in a wireless transceiver, the method comprising:
receiving wireless downlink signals in a downlink frequency band having a first set of subcarriers;
determining a virtual uplink resource allocation within an uplink frequency band that is distinct from the downlink frequency band, wherein the uplink frequency band has a second set of subcarriers distinct from the first set of subcarriers, and wherein the uplink frequency band has a second bandwidth distinct from a first bandwidth of the downlink frequency band; and
transmitting an uplink signal in an uplink resource allocation associated with the virtual uplink resource allocation.
17. The method of claim 16 , wherein receiving the wireless downlink signals comprises receiving downlink Orthogonal Frequency Division Multiplex (OFDM) symbols over the first set of subcarriers.
18. The method of claim 16 , wherein receiving the wireless downlink signals comprises receiving the wireless downlink signals in a downlink time period exclusive of an uplink time period.
19. The method of claim 16 , wherein determining the virtual uplink resource allocation comprises determining a subcarrier allocation in at least one uplink Orthogonal Frequency Division Multiplex (OFDM) symbol, the at least one uplink OFDM symbol having a distinct number of subcarriers from a downlink OFDM symbol.
20. The method of claim 16 , wherein transmitting the uplink signal comprises transmitting an Orthogonal Frequency Division Multiplex (OFDM) symbol occupying an uplink bandwidth distinct from a downlink bandwidth.